Rain sensor for detecting rain or other material on window of a vehicle or on other surface

Abstract

A system and / or method for sensing the presence of moisture (e.g., rain) and / or other material(s) on a window such as a vehicle window (e.g., vehicle windshield or backlite). In certain example embodiments, a capacitor-based system and / or method is provided for auto-correlating sensor data to determine the existence of a material on the window, and then cross-correlating sensor data to identify the type and / or amount of that material (e.g., rain). This data may be used to actuate and / or deactivate a vehicle's wiper(s), and / or adjust wiper speed. In certain example embodiments, the sensor may include an array of at least two capacitors. In certain example embodiments, the system and / or method may perform check(s) to enhance the accuracy of the detection by comparing, for example, the sign of autocorrelation values, maximum autocorrelation values, and / or gradients of autocorrelation values

Description

[0001] This application claims priority on U.S. Provisional Patent Application No. 60 / 757,479, filed Jan. 10, 2006.FIELD OF THE INVENTION [0002] This invention relates to a system and / or method for sensing the presence of rain and / or the disturbances or presence of other materials on a sheet(s) of glass such as a vehicle windshield. In certain example non-limiting embodiments, a system and / or method is provided for auto-correlating sensor data (e.g., data from one or more capacitors) to determine whether it is likely that a material such as moisture (e.g., water) is present on a sheet of glass. Optionally, in certain example embodiments, cross-correlation of sensor data may be performed to identify the type and / or amount of material present on the glass. In certain example embodiments, cross-correlating may be used without auto-correlating. In certain example embodiments, results of the correlation(s) may be used to adjust a vehicle's wiper speed, and / or a wiper's actuation and / or s...

AI Technical Summary

Benefits of technology

[0003] The presence of moisture (e.g., rain or condensation) and / or other material or debris on vehicle windshields and / or backlites may create hazardous driving conditions for drivers, passengers, and pedestrians if not promptly removed. Wiper blades are a well-known, common way to remove such materials and reduce the hazards of driving during dangerous conditions. Rain sensors have been developed to detect the presence of moisture (e.g., rain or other condensation) on a vehicle windshield, and to turn on and off wipers, as necessary, when such moisture is detected. Automatically detecting rain, sleet, fog, and the like, and taking appropriate action—for example, turning on / off wiper blades at a proper speed—potentially reduces distractions to the driver, allowing the driver to better concentrate on the road ahead. However, inappropriately turning on / off wipers or failing to actuate wipers when moisture is present may also create hazardous conditions. Moreover, such systems are also susceptible to “dirt” distractions which may cause false reads / wipes when dirt is on the windshield.

[0017] In certain example embodiments of this invention, capacitors are formed based on a fractal pattern. For example and without limitation, one or more of the capacitors may be formed based on a fractal pattern, such as a Hilbert fractal pattern. Other capacitive fractal patterns may also be used, including but not limited to a Cantor set. These fractal structures maximize or enlarge the periphery and thus result in a large capacitance for a given area. The use of two dimensional fractal designs also allows the sensor to occupy a small amount of physical space on the window while at the same time being electrically larger than its physical size. The concentration of lateral flux in a fractal geometry may also allow the sensor to detect rain / water not necessarily spread over the actual physical area of the sensor in certain example embodiments of this invention. Furthermore, in its higher iteration(s) a fractal capacitor(s) has an attribute of being its own Faraday shield or quasi-Faraday shield. Also, in certain example embodiments, the rain sensor may be electrically connected to a Local Interconnect Bus of the vehicle.

Problems solved by technology

The presence of moisture (e.g., rain or condensation) and / or other material or debris on vehicle windshields and / or backlites may create hazardous driving conditions for drivers, passengers, and pedestrians if not promptly removed.

However, inappropriately turning on / off wipers or failing to actuate wipers when moisture is present may also create hazardous conditions.

Moreover, such systems are also susceptible to “dirt” distractions which may cause false reads / wipes when dirt is on the windshield.

However, these optical techniques have limited sensing areas, are fairly expensive, and may result in erroneous detection indications due to the use of optical imaging as the sole detection method.

Unfortunately, the system of Tenenbaum suffers from certain disadvantages.

The Tenenbaum optical system is susceptible to erroneous detections due to its reliance solely on optical imaging, and has a limited sensing area.

This necessitates expensive optical components while requiring computationally intense data analysis, while the system is still subject to the above disadvantages.

Without naturally occurring ambient light (e.g., at night), the system will not properly function.

LEDs may be used, but this tends to make the system more complex and / or expensive, with additional potential points of failure.

Moreover, when using LEDs in the manner disclosed by Tenenbaum, the system can be confused by sudden changes in ambient light.

For example, sudden changes in ambient light may occur when going through a tunnel, coming around a corner and suddenly facing the sun, driving through a city with skyscrapers that block the sun, etc., thereby leading to a potential for false readings / detections and false wiper actuations.

Unfortunately, Netzer's system also has significant disadvantages.

Thus, for example, if there is already moisture (e.g., rain or condensation) on a windshield because a vehicle was parked outside during a rain shower or fog, Netzer's system may not detect the same when the vehicle is started.

Moreover, Netzer's system may be subject to certain detrimental effects of electromagnetic interference (EMI), temperature changes, as well as interference from other sources.

For instance, as external bodies (e.g., human hand, radio waves, etc.) interfere with the function of the capacitors, the charges of the excitation and receiver electrodes may uncontrollably vary in Netzer, thereby leading to false alarms or detections.

Thus, for example and without limitation, with Netzer's system, CB radios, microwaves, handheld devices, human contact with the windshield, groundable objects, and / or the like may undesirably interfere with the system, and thus possibly produce false wipes and / or detections.

Netzer's system is also subject to possible false reads caused by drastic temperature changes in view of the reference capacitor system utilized by Netzer, where Netzer's reference capacitor has a different geometry / shape / size than the sensing capacitor.

These fractal structures maximize or enlarge the periphery and thus result in a large capacitance for a given area.

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